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Image correlation displacement sensor

a displacement sensor and image technology, applied in the field of image correlation displacement sensors, can solve the problems of difficult to measure displacement along a direction perpendicular to the target surface, limited direction of displacement to be measured, etc., and achieve the effect of simple configuration and high accuracy

Active Publication Date: 2014-04-08
MITUTOYO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an image correlation displacement sensor that can accurately measure displacement in a simple way. This sensor can measure displacement along a direction that includes a component perpendicular to a target surface.

Problems solved by technology

In the image correlation displacement sensor that measures a displacement by capturing speckle fields, however, the direction of the displacement to be measured is limited.
In other words, speckle fields are generally imaged along a direction that is normal to a receiving surface of a detector as well as normal to the target surface, which makes it difficult to measure a displacement along a direction perpendicular to the target surface.

Method used

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first exemplary embodiment

[0020]An image correlation displacement sensor according to a first exemplary embodiment of the present invention is described with reference to FIG. 1. FIG. 1 is a diagram schematically showing the overall configuration of the image correlation displacement sensor (hereinafter abbreviated as “displacement sensor”). A displacement sensor 100, which measures a displacement of an object to be measured having a target surface 300, includes an illumination portion 130, an imaging portion 240, and a processing portion 200. The displacement sensor 100 is mounted in a measuring head, for example.

[0021]For clarity of explanation, the image correlation displacement sensor according to the first exemplary embodiment is described using a three-dimensional Cartesian coordinate system. Referring to FIG. 1, a Z-direction is parallel to an input optical axis of an optical system 250 (described in greater detail below), an X-direction is perpendicular to the Z-direction and parallel to a row or col...

second exemplary embodiment

[0069]A displacement sensor according to a second exemplary embodiment of the present invention will be described with reference to FIG. 5. FIG. 5 is a diagram showing a second exemplary configuration of the displacement sensor 100. The displacement sensor 100 according to the second exemplary embodiment includes a second embodiment of an illumination portion 130′, described further below. Otherwise, the second embodiment is a simplified form of the displacement sensor 100 according to the first exemplary embodiment, and is configured to use fewer optical paths to perform a three-degree of freedom measurement, for the translational degrees of freedom. The yaw displacement degree of freedom (a fourth DOF) may also be determined in some applications, as outlined further below. To perform the three-degree of freedom measurement, only the two optical paths A and B′ are used, and thus the element 110 includes a single optical deflector element DefA. The detector 160 includes the detectio...

third exemplary embodiment

[0076]A displacement sensor 400 according to a third exemplary embodiment of the present invention will be described with reference to FIG. 6. The configuration of the third exemplary embodiment differs from that of the first exemplary embodiment in the configuration of the telecentric optical system. The basic configuration of the displacement sensor 400 is similar to that of the first exemplary embodiment, so a description thereof will be omitted as appropriate. Hereinafter, the configuration of an imaging portion 440 will be mainly described.

[0077]In the third exemplary embodiment, each of the optical paths A to E is provided with a separate lens 140. Accordingly, on the rear side of the element 110, five lenses respectively corresponding to the optical paths A to E are disposed. To simplify the explanation, assume that the lens corresponding to the optical path B is a lens 140B, and so on for the other optical paths. The lens 140B affects only the optical path B. Similarly, the ...

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Abstract

An image correlation displacement sensor for measuring a displacement component along a direction perpendicular to a target surface, with a simple configuration. The sensor may include: an illumination portion (130′) which emits illumination light; an imaging portion including at least two optical paths (A and B′) which are used to capture multiple images of a speckle field produced by the target surface (300), one of which (A) is inclined with respect to a normal to the target surface in proximity to the target surface, and an element (110′) which deflects an at least one of the optical paths (A and B′); and a processing portion (200) which measures a displacement relative to the target surface along a direction which includes a component normal to the target surface (300) in accordance with the correlation of multiple images captured in the optical paths (A) and (B′).

Description

INCORPORATION BY REFERENCE[0001]U.S. Pat. No. 6,642,506, filed on Jun. 1, 2000, U.S. Pat. No. 7,295,324, filed on Jul. 13, 2004, and U.S. Pat. No. 7,515,280, filed on May 12, 2004, are each hereby incorporated in its entirety by reference.BACKGROUND[0002]1. Field of the Invention[0003]The present invention relates to an image correlation displacement sensor, and more particularly, to an image correlation displacement sensor that captures speckle fields to measure a displacement of an object.[0004]2. Description of Related Art[0005]Image correlation displacement sensors using a correlation between a plurality of speckle fields (speckle images) are known (see U.S. Pat. Nos. 6,642,506; 7,295,324; and 7,515,280). In general, a coherent light source such as a laser light source is used for each image correlation displacement sensor. A speckle field is produced by illuminating an optically rough surface with the coherent light source. Specifically, a target surface is illuminated with coh...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): H04N5/30
CPCG06T2207/10016G01B11/16G06T7/0026G01B11/00G06T7/32
Inventor TOBIASON, JOSEPH, DANIEL
Owner MITUTOYO CORP